Electromagnetic signal-indicator.



No. 735,953. PATENTED AUG. 11, 1903. E W. W. DEAN.

ELECTROMAGNETIC SIGNAL INDICATOR. APPLIOATION FILED JAN. 14, 1902. N0MODEL UNITED STATES Patented August 11, 1903.

PATENT OFFICE.

WILLIAM W. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRICCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTROMAGNETIC SIGNAL-INDICATOR.

SPECIFICATION formingpart of Letters Patent No. 735,953, dated August11, 1903.

Application filed January 14, 1902. erial No. 89,659. (No model.)

To all whom it may concern:

Be it known that I, WILLIAM W. DEAN, a

, citizen of the United States, residing at Ohicage, in the county ofCook and State of Illinois, have invented a certain new and usefulImprovement in Electromagnetic Signal- Indicators, of which thefollowing is a full, clear, concise, and exact description.

My invention relates to an electromagnetic signal-indicator, and has forits object to pro-' vide an efficient self restoring indicator which issimple in construction, having few parts, and not liable to get out oforder.

A further object is to make the signal selfcontained, so that it mayreadily be removed as a whole from its mounting without taking apart.

My invention consists in certain details of construction hereinafterdescribed, and particularly pointed out in the appended claims.

I will describe my invention by reference to the accompanying drawings,which illustrate the preferred embodiment thereof, wherein- Figure 1 isa longitudinal sectional view of the indicator. Fig. 2 is a similar viewshowing the parts in position to display the signal. Fig. 3 is a planview. Fig. 4 illustrates the front of a row of signals, and Fig. 5 is adetail perspective view of a portion of the mechanism. 7

Similar letters of reference are used to designate the same parts inwhatever figures of the drawings they may appear. I

The core a is surrounded by a magnetizing helix 1) and is secured at theright-hand end to the base of a U-shaped pole-piece c, the arms 0 c ofwhich pole-piece inclose the core and its helix. This pole-piece may beformed of an iron plate one-sixteenth of an inch in thickness, an inchwide, and nine inches long, bent'into a U shape, with the base:square. Ascrew a passes through the base of the U into the end of the core tohold the same in place, and two screws 0 0 also pass through the arms 00 into the insulating end piece I) of the electromagnet. The arms 0 care longer than the core a, so that the ends project some distancebeyond the end of said core, forming an inclosure in which the ro- 5otating armature e of the electromagnet is mounted. The ends of the arms0 c are joined by a non-magnetic plate (1, having an opening 61', inwhich a target is adapted to be displayed. In practice a number of theindicators are mounted in a row, as shown in Fig. 4:, the plates 61 d of'the several indicators being each secured by a screw (1 to a cross-bard Arotatingarmatureispivoted or trunnioned in the arms 0 c in positionto be attracted by theend of the core a. This armature preferablyconsists of a stirrup-shaped iron piece e, pivoted in front of themagnet-pole a and having a tapered tongue 6', bent upward from the basetoward the magnet-pole. This tongue is preferably curved eccentrically,so that as the armature rotates in a contra clockwise direction it willgradually approach the magnet-pole. A projection e also eX- tendsdownward from the left-hand lower a position directly under themagnet-pole when the armature is rotated, as shown in Fig. 2, so that adirect upward pull is exerted upon the armature as it approaches ahorizontal position. This projection also acts as a stop to limit themovement of the armature when it reaches a horizontal position. A smallpiece e of non-magnetic metal may be provided upon the face of thisprojection to prevent it from sticking to the magnetpole when currentthrough the magnetizinghelix ceases.

' A light aluminium shield fis carried upon the upper end of thearmature-stirrup above the pivotal point thereof, which shield isnormally concealed from view from the front when the armature hangs inits normal vertical position; butwhen the magnet is excited and attractsits armature the shield is swung down into the opening d in the plate d,thus The armature and the shield form a rectangular framework, as shownin Figs. 3 and 5, the shield or targetf being carried at the top of thisframework and the armature properthat is, the part which is directlyacted on by the magnet-poleat the lower end. A shaft 71. is passedtransversely through this framework and secured thereto, said shafthaving extensions 71 h of smaller diameter which serve as trunnions uponwhich the framework rotates. These trunnions rest in holes provided forthe purpose in the two arms c of the U-shaped pole-piece c.

The framework of Fig. 5 constitutes in its essentials acentrally-pivoted rocking arm, one end of which carries a shield ortarget and the other end whereof carries an armature, said armaturebeing adapted to be attracted by the pole of the electromagnet,

which is preferably on the level with the.

pivot of the rocking arm, the armature being preferably formed with atapered tongue bent into an arc eccentric to the pivot, whereby thesurface of the armature gradually approaches the magnet-pole as the armis rotated, said arm being adapted to be rotated to display the shieldor target when the magnet is excited.

The signal-indicators of my invention may. be used with advantage asline-signals for telephone-exchange switchboards. They may be mountedside by side upon a metal strip t', passing along the back of theswitchboard, and it will be appreciated that each signal-indicator isself-contained and may be removed as a whole from its mounting withoutthe necessity of taking it apart or disturbing the mechanism in any way.

A feature of my invention consists in making the shield or target fconvex or partly spherical in form, so that it will fit closely as wellas from the front.

into the circular opening (1 inlthe plate (1 and will project a littlebeyond the surface of the plate. A target of this form will be noticedmore quickly by the eye of the operator and will attract attention fromthe side A fiat target could not be seen so readily from the side.

I claim as my invention- 1. In an electromagnetic signal, thecombination with an electromagnet, of a centrallypivoted rocking arm, acurved eccentric armature carried by one end of said rocking arm inposition to be attracted by the magnet-pole, whereby said arm is adaptedto be rocked when the magnet is excited, and an indicator or shieldcarried by the opposite end of said rocking arm, as set forth.

2. In an electromagnetic signal, the combination with an electromagnet,of a centrallypivoted rocking arm, a tapered eccentric armature 6carried by one end thereof in posi tion to be attracted by themaguet-pole,whereby said arm is rocked when the magnet is excited, and ashield or target carried by the other end of the rocking arm, as setforth.

3. In an electromagnetic signal, the combination with a magnet-core, amagnetizinghelix disposed about said core and a U -shaped pole-piece forone endof the core, the core and helix lying between the arms of saidpolepiece, the-arms of said pole-piece being longer than the core andprojecting beyond theend of the same, of a rocking arm of magneticmaterial pivoted in the projecting arms of the U-shaped pole-piece, anarmature carried by one end of the rocking arm, an indicator or targetcarried by the other end thereof and a plate in front of said magnethaving an opening in which the target is adapted to be dis played whenthe rocking arm is swung into its attracted position, as set forth.

4. In an electromagnetic signal, the combination with an electromagnet,of a pair of arms 0 0 extending in front of the end of said magnet oneach side thereof, a rectangular framework pivotedin saidarms andnormally hanging in a vertical position, a target or indicator carriedat the top of the framework, a curved eccentric armature carried at thelower end thereof, said armature having a tapered tongue e which iscurved in an arc eccentric to the pivot, whereby the surface of' thearmature gradually approaches the magnet-pole as the frame is rotated,and a shield or plate having an opening in which the tar get is adaptedto be displayed when the framework is rotated, substantially asdescribed.

5. In an electromagnetic signal, the combination with a magnet-core, amagnetizinghelix therefor and a U-shapedpole-piece secured to the coreat one end, the arms of said pole-piece being longer than the core andpassing back substantially parallel therewith, a

shield or plate uniting the ends of the polepiece and having an openingtherein, a rocking arm pivoted in the arms of the U-shaped pole-piece,between the said shield and the magnet-core, a target or indicatorcarried by one of said rocking arms, and an armature carried by theother end thereof, substantially as described.

6. The combination with an electromagnet, of a U -shaped pole-piecetherefor fastened to the magnet-core at one end, the arms 0 c of saidpole-piece projecting beyond the other end of the magnet, and astirrup-shaped armature c pivoted in said arms 0 c and normally hangingin a vertical position, said armature having a tapering tongue 6 curvedeccentrically, as set forth.

7. In a signal indicator, the combinatio with a plate having an openingd therein, of a convex or rounded target f shaped to fit closely in andconform to the outline of said opening, the convex body portion of saidtarget bulging outward through said opening beyond the plane of theplate, said target being pivoted to swing into or out of said opening,and a magnet for moving the target.

8. In asignal, the combination with an electromagnet, of a shield infront of said magnet, having an opening therein, a rocking arm pivotedtransversely to hang substantially Vertical between the end of themagnet and the shield, a target carried at one end of said rocking armand a tapered armature-tongue carried at the other end, said tonguebeing curved tangentially from the end face of said arm toward the endof the magnet, whereby said rocking arm is swung about its axis intosubstantial alinement with the magnet to display the target in theopening of the shield when the magnet is excited. I0

In witness whereof I hereunto subscribe my name this 5th day of October,A. D. 1900. WILLIAM W. DEAN. Witnesses:

ELLA EDLER, ADELL HOCKETT.

